The most common and most likely answer to this crossword clue is the 8 letter word VAGRANTS
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More clues leading to the result VAGRANTS
Buddy explains!

The straight part
We know that "bums" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case bums = vagrants.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does VAGRANTS mean?
VAGRANTS noun- A person who wanders from place to place; a nomad, a wanderer.
- (specifically) A person without settled employment or habitation who supports himself or herself by begging or some dishonest means; a tramp, a vagabond.
- Vagrans egista, a widely distributed Asian butterfly of the family Nymphalidae.
- An animal, typically a bird, found outside its species' usual range.